1. Field of the Invention
The present invention relates to a measurement device for the distribution of chemical concentration in the solution. The device consist of a semiconductor and a material-sensitive film that a pulsed laser beam is irradiated and electromagnetic waves generated in the semiconductor is detected so as to detect whether a material to be detected exists in a solution or not. In detail, the present invention relates to a device for detecting reaction distribution or concentration distribution of a material present within a microflow channel for a chemical reaction in the solution.
2. Background Art
Conventionally, as a device for detecting a material in a solution, there is a sensor with a field-effect transistor. The sensor with the field-effect transistor generally includes (1) a sensitive film provided on a gate electrode of the field-effect transistor, (2) a sensor readout circuit reading out a signal from a drain electrode and a source electrode, (3) a power source for driving the sensor, and (4) a reference electrode for stabilizing electric potential of the solution.
In the sensor with the field-effect transistor constructed as the above, when a material to be detected included in a solution touches the sensitive film, the material is decomposed by catalysis of the sensitive film so that pH of the solution is changed. Then, a current of a local electric field of a semiconductor in the field-effect transistor changed by the change of pH is detected as a signal with the drain electrode and the source electrode.
There is provided a method for detecting a plurality of materials by arraying such sensors with field-effect transistors (sensor elements) on the same substrate (for example, see the Patent Literature 1).
The Patent Literature 1 describes a method for producing 100 pairs of sensor elements on a substrate of 50 mm×60 mm by patterning with photoresist.
The Patent Literature 2 describes a p-channel field-effect transistor and a sensor therewith that enzyme is directly fixed to a surface of a FET channel (a surface of a diamond) so as to improve sensitivity of the enzyme.
The Patent Literature 3 describes a method and device for failure diagnosis of a semiconductor device which can perform failure diagnosis under no bias with a pulsed laser beam without applying bias voltage on a chip (semiconductor device).
Furthermore, as a material detecting device with a laser beam, there is known a LAPS (Light-Addressable Portentiometric Sensor) (for example, see the Non-patent Literature 1). The LAPS includes a semiconductor silicon substrate and a sensor substrate, which includes an oxide film and a nitride film formed on the semiconductor silicon substrate, and is used, for example, as a sensor for measuring pH of a solution touching the sensor substrate.
An energy band curves in the interface between the semiconductor silicon substrate and the sensor substrate, and the curve also depends on pH of the solution touching the sensor substrate. As a result, width of a depletion layer in the interface between the semiconductor silicon substrate and the sensor substrate changes, whereby a current flowing at the time of irradiating a laser beam (photocurrent) changes.
As mentioned above, the current flowing at the time of irradiating the laser beam (photocurrent) is influenced by the change of width of the depletion layer at the point to which the beam is irradiated.
Detecting devices and detecting methods for detecting a material in a microflow passage have been examined. For example, as a detecting device for a material with surface plasmon, there is known a sensor with a SPR (surface plasmon) sensor. The SPR sensor is used with a method that a beam is irradiated to a floor surface of the microflow passage at a fixed angle and a spectrum of the total reflection beam is used for analysis.    Patent Literature 1: the Japanese Patent Laid Open Gazette 2002-350383    Patent Literature 2: the Japanese Patent Laid Open Gazette 2004-294087    Patent Literature 3: the Japanese Patent Laid Open Gazette 2006-24774    Non-patent Literature 1: T. Yoshinobu et al., Electrochimica Acta, Vol. 47 (2001) pp. 259-263